Projectile having its center of gravity in front of the center of resistance



Sept. 5, 1939. A. 0| BRAZZA-SAVORGNAN PROJECTILE HAV ING ITS CENTER OFGRAVITY IN FRONT OF THE CENTER OF RESISTANCE Filed July 15, 1956Patented Sept. 5, 1939 UNITED STATES PROJECTILE HAVING ITS CENTER OFGRAVITY IN FRONT OF THE CENTER OF RESISTANCE Ascanio diBrazza-Savorgnan, Rome. Italy Application July 15, 1936, Serial No.90,632.

In Italy July 18, 1935' 2 Claims.

The object of the present invention is to provide a projectile whichdoes not tend to turn over during its trajectory (and therefore shootsaccurately) evenif shot from smooth bore firearms.

Until now, it has been attempted to attain this object by applying toprojectiles shot from firearms, the prehistorical principle of thearrow, javelin, etc.

In these, the stabilizing action of the air, acts on the tall or rearportion of the projectile, but it is evident that it ceases to fulfilits functions when the velocity of the projectile during its trajectory,is high enough as to produce a vacuum (or something practicallyequivalent) around the said rear part of the projectile.

This rear part is then deprived of the support of the surrounding air,and nothing prevents the projectile from behaving as any missilestarting its'travel through the air, with its center of gravity in arearward position with respect to its center of resistance, withoutbeing provided with stabilizing means, as for. instance with rotationimparted by rifled gun barrels.

As the head or fore portion of the projectile is hampered in its forwardmotion by the cushion of compressed air which it drives in front ofitself during its flight, a projectile having its center of gravityinthe position above mentioned, and not having any rotary movement roundits axis, will rest on said cushion of compressed air, will be in acondition of unstable equilibrium and will consequently have a tendencyto overturn.

In both cases anyhow, the accuracy of the shot is lost. I This happensalready with much lower velocities of flight of the projectile, than thevelocities obtained with a common shotgun, using a single bullet and anormal propelling charge.

The named principle of the arrow, etc., applied to projectiles destinedto be shot from firearms, is therefore only eflicient,if theseprojectiles possess very low velocities of flight, as for instance thebombs shot from smooth bore mortars, with very small propelling charges.

tioned projectiles, however, owing to their low velocity of flight,possess only. a relatively short range, and if their. velocity isaugmented by increasing the propelling charge, their range mightincrease, but the accuracy of the shot is lost.

One of the objects of the present invention, besides its application tosporting guns, is also to provide for military purposes, a projectilefor smooth bore mortars, capable of flying without turning over, even ifshot with a very high muz- These last men-- zle velocity; and possessingtherefore a very long range of accurate shooting.

The present invention is based on the following principles.

(1) To obtain the stability of projectiles of cer- 5 tain shapes, duringtheir flight, by the pressure of the air on their anterior portion,orhead or nose as it may be called. I

(2) To determine-the position of their center of resistance, i. e., theresultant of the resistances 1 opposed by the air to-the motion of theprojectiles along their whole trajectory.

(3) To give to these projectiles such shapes, proportions andcomposition, that their center of gravity is placed, during their wholetrajectory, in front of their center of resistance.

The accompanying; drawing shows schematically and by way of example someforms of real- 'ization of the object of the invention, in which:

Figure 1 shows a projectile of spherical shape, 20

in which a segment of its rear portion has been out off.

Figure 2 shows a projectile having a semispherical head and acylindrical rear portion.

Figures 3 and 4 show projectiles having a more elongated cylindricalrear portion, with heads formed as spherical segments of differentheight and curvature.

Figures 5, 6, 7 and 8 show projectiles in flight along theirtrajectories and the rear limit of their 30 compression wave.

Figures 9, 10 and 11 show three forms of removable rings, provided withone or moreslots, for setting of "the projectile in its cartridge.

Figure 12 shows in section thefore part of a shot gun cartridge, with aprojectile on which a trimming ring' is superposed as that shown, in

" Figures 9, 10 and 11.

The stability of a pro ectile obtained through the pressure of the airon its head instead of the stability obtained by-the action of the ar onits tail, has the obvious advantage that the former is a factor which,instead of failing, is more than ever efiicient, even at the highestvelocities of flight of the projectile. 45

As to the center of resistance, applicant started from the suppositionthat, in a projectile with its head shaped as'a semisphere or as aspherical segment of suflicient curvature and height, this center ofresistance corresponds almost exactly, and in any case with very greatapproximation, to the center of curvature of the semisphere or of thespherical segment.

As to the center of gravity of a projectile having its anterior partshaped as described, if one is not bound by any particular weight orlength to be given to the same projectile, it is an easy matter to makeit coincide with a point of the longitudinal axis of the saidprojectile, fixing surface, for instance on a mirror, resting on itsrounded head. 7 r

If in this position the projectile can oscillate without falling down,it answers the purpose, but if it falls to one side, it does not answerthe purpose. I

The correctness of the supposition concerning the correspondence of thebefore named center of curvature with the center of air resistance, wasconfirmed by experience as, after many causes of disturbance had beeneliminated, it resulted that none of the projectiles which couldoscillate in the named manner on a mirror, would turn over during itsflight, at a distance of 100 metres (nearly 110 yards) at which distanceexperiments were chiefly made, whereas if they overturned on a mirror orsimilar flat surface, they struck the target more or less sideways.

In said experiments, the muzzlevelocities measured at an oflicialexperimentingstation,were of around 385 meters (1262 feet) per secondwith a 12 gauge projectile weighing 33 grammes (nearly 510 grains) andshot from a full choke Browning shotgun. I

The highest velocity triedrwas up to 741.9 metres (2432 feet) persecond, with a little bullet of the diameter of 7.2 millimetres,weighing 2.05

rammes (a little over 30 grains) and shot from a military carbine, therifling of which had been taken away.

Also bullets as heavy as 730 grains, were shot from a 12 gauge shotgun.

Of the latter, the velocity was not measured but they all struckthe'target in head-on position.

The great diflerence in weight and size, and

. also (within certain limits) 'of shape of the proiectiles tried atvery different velocities, some of which as high as those stated,undoubtedly confirm the correctness of the supposition of the inventor,concerning the correspondence of the center of curvature of the head,with the center of air resistance, in projectiles having the head oftheshap'e abovev described. i

The exper'ments have also shown, within the limits of volocities tried,that this correspondence does not practically change, with the change ofvelocity, and also evidently does not change with respect to theoscillations of the projectile, along its trajectory, 'to which everyprojectile is more or less subjected during its flight.

To come to the shapes to be given to projectiles, in order that theyshould realize the object of the present invention, these shapes donotdifl'er from those already known, but the novelty consists in findingthe exact measures and proportions which must be given to the same.

A shape answering theoretically the aforesaid conditiomwould also be theone shown on Figure and grooves.

According to applicant, there still remained two all dimensions 1, whichsimply represents a sphere in which a segment of what would have beenits rear portion, has been cut away.

In practice however, this shape has not been found advisable as comparedwith other shapes hereinafter described.

Another shape would be like the one shown on Fig. 2, which represents aprojectile having a fore part of head I shaped as a half sphere, and arear part 3 shaped as a cylinder having the same radius as the sphere,and such height so that its volume (and weight) is equal to that of thefore half sphere.

Such height may be easily calculated, and results to be two thirds ofthe radius of the sphere.

The whole projectile has thus the same volume and weight, as a sphericalone having the same diameter. I

Also the position of the center of gravity of a projectile of such ashape, is easily calculated, and is situated above the center ofcurvature of the semispherical part, at a distance equal to A of theradius of the same. This might seem little, but experience has shown itto be sufilcient in practice. Said distance is certainly not excessiveand cannot therefore be substantially diminished. It shows besides, thata slight imperfection or deformation of the form, or a little alterationof its proportions is suflicient to produce an inaccurately shootingprojectile, instead of a very accurately shooting one.

In Figures 1 to 4 the distance between the center of gravity b; and'thecenter of curvature c has been exaggerated for the purpose of showingthese two points separately.

If projectiles of the design above mentioned weredestined to be usedwith smooth cylinder bore barrels, they could be made exactly as shownin Figure 2, and having such diameter as to fit exactly the bore of thegun,- in respect to which bore they would then possess a sufficientweight. If, however, they were to be used with choke bore barrels (asalmost all actual shotgun barrels are) their diameter would have to bereduced so as to enable thm to pass easily through the narrowest choketype of barrels.

In this condition (as it has been confirmed by experience) theiraccuracy could only be satisfactory, if their cylindrical part beprovided, with some of the known devices (used since the early years of"this century) to guide a slug truly through the bore of a chokedbarrel.

As it is known, these consist of a longitudinal, oblique or annular ribsand grooves.

Experience has also shown that there is no difference in the accuracy ofshooting of projectiles provided with these diiferent kinds of ribsdefects to a projectile of this shape and size, with reduced inproportion to its reduced diameter.

One consisted in the insuillcient weight (about one ounce for 12 gauge)which is considered too little not only by applicant but generally inEurope, for projectiles"of that kind.

The other defect (although in practical experience, it gave no troublewith, carefully loaded shells and suitable powder) was that. thecylindrical part (or to be more exact, substantially cylindrical as thenamed devices had somewhat modifled it) was very low, so that in passingfrom the shell to the bore of the barrel, the bullet might not have beenguided enough, to be pre- 75' vented from entering the oblique position.v

Lengthening the cylindrical part, without displacing rearwards thecenter of gravity, meant lightening that part (through cavities orthrough the use of lighter materials) and therefore the whole bullet,already considered too light by applicant. vTo get a heavier bullet ofthe same diameter and with a longer cylindrical part, and maintainingthe required relationship between center of curvature and center oigravity, the radius of what-had been the semispherical part, wasaugmented.

This part got thus the shape oi a spherical segment 2 as shown on Fig. 3which shows that all the desired requisites were fully maintained. InFig.4 these characteristics are augmented.

As already said, applicant experimented with success bullets as heavy as730 grains, in a 12 gauge shotgun.- He himself does not consider thisweight advisable as a rule, but he made this experiment to show that theso-called, Paradox or ball and shot guns, which shoot bullets of thisweight, are by no means superior to an ordinary shotgun, loaded with abullet, made according to his invention.

There is evidently a limit in increasing the radius of the sphericalsegment forming the head of the bullet,- and the consequent flatteningof the same. In fact, for the projectiles of the shapes described, it isevidently advisable that, even with the maximum oscillations that theprojectile may be subjected to, during its flight, the rear limit of thecompression wave 1n=1t (Figures 5, 6, 7 and 8) must not arrive to touch(Figures 5, 6) or at the maximum may reach the base of the sphericalsegment (Figure 7). It the condition shown in Flgure8 should berealizeed, the oscillations of the projectile would probably cause theline m=1r to be modified, i. e., the support of the projectile itself,and this would probably cause its upturning. The limit to which theradius of the spherical segment can be augmented, and consequently itscurvature and its height can be reduced, without endangersame, in asomewhat ing the stability oi the projectile, is evidently a function ofits velocity and this limit may be determined by experiment.

In loading game shooting cartridges, applicant has found it advantageousto provide the projectile with an annular wad I (Figures 9, 10, 11 and12) of suitable thickness, cut in a point (Figure 9) or preferably intwo or more points at even distances (Figures 10 and, 11).

This allows the bullet to be well protected within the shell, and notgiving trouble by projecting out of the same, if used with repeating orself loading guns.

This allows also to give to the cartridge a good turnover and acorrect-opening at the moment of the shot, which might otherwise causesome trouble, owing to the convex shape of the head of the projectile.This is shown in Figure 12, in which 4 is the annular wad cut in t, p isthe projectile, s is the usual wad, interposed between the charge 0!powder and the projectile, and o is the cartridge edge turned over.

As the said annular wad is cut in a point or, divided in several partsas above mentioned, the

of gravity ofthe whole projectile is disposed in front of the center ofcurvature of said forward part.

2. Projectile according to claim 1, in combination with a cut annularwad, adapted to be superposed upon the projectile in the cartridge, so,that the turn over of the latter is caused to rest on the face of saidout wad, in order to hold 2 it in place.

ASCANIO n1 BRAZZA-SAVQRGNAN.

